The invention relates generally to the field of automotive chassis. In particular, the invention relates to a lightweight spindle for use in automotive vehicles.
Metal spindles are utilized in automotive vehicles to support the wheel bearing and provide a connection of the wheel bearing to the chassis. Modern spindles are commonly manufactured from high-strength steel and are constructed from two pieces, the stem and the knuckle.
The stem of a spindle is commonly a cylindrical piece made from high-strength steel. The stem provides a mounting point for the wheel of a vehicle, and the stem connects to a knuckle, which is connected by rods to the chassis of the vehicle. The usual connection point between the stem and the knuckle is an opening defined in the knuckle.
The knuckle of a spindle is also constructed of a high-strength steel and connects the spindle to the chassis of the vehicle. The knuckle has an opening defined in it to provide a connection point for the stem of the spindle.
There are varying methods of providing a reliable connection between the stem and the knuckle of the spindle. One method is to construct the stem so that the outer diameter of the stem is slightly larger than the inner diameter of the opening defined in the knuckle of the spindle. The stem is then mechanically pushed into the opening in the knuckle. This method requires the use of high-strength steel in both the stem and the knuckle to prevent deformation of either piece.
Another method also utilizes a stem with an outer diameter slightly greater than the inner diameter of an opening in the knuckle, but connects the two pieces in a different manner. In this method, the opening in the knuckle is heated until it is enlarged, and then the stem is mechanically pushed into the opening. Again, high-strength steel is required for both pieces.
The use of high-strength steel creates a strong supporting spindle and reduces harmful deformation, but at the cost of adding extra weight to the vehicle. It is desirable to construct a spindle that provides a comparable amount of support, yet is also as lightweight as possible.
In one embodiment of the present invention, a spindle for use in an automobile chassis is provided. An aluminum knuckle with an axial through hole defined in its interior is provided along with a substantially cylindrical steel stem with an interlocking feature defined on one end. The interlocking feature has an extended flange with an outer diameter greater than the inner diameter of the through hole in the knuckle. The interlocking feature also has a frusto-conical section and at least a portion of the stem is welded to at least a portion of the through hole such that the interlocking feature is within the through hole.
In a second embodiment of the present invention, a spindle for use in an automobile chassis is provided. An aluminum knuckle with an axial opening defined in it and a substantially cylindrical steel stem are provided. The stem has an interlocking feature defined on one end and the interlocking feature is friction-welded into the axial opening of the knuckle.
In yet another embodiment of the present invention, a method of forming a spindle for use in an automobile is provided. The method comprises the first step of providing an aluminum knuckle and defining an axial through hole in it. The next step is to provide a substantially cylindrical steel stem with an interlocking feature defined on one end and align the stem with the through hole. A rotational force is applied to the stem and axial pressure is applied to the stem to mount the interlocking feature into the through hole.